NSTokenField suggestion is slow:what is the process?

Question

NSTokenField takes quite a time to propose suggestion to the text I enter. More precisely, here is what happens:

1. I type the letter "a"
2. the method textDidBeginEditing: of NSTokenField is called immediately
3. some time (approx. 1/2 to 1 second)
4. the method tokenField:completionsForSubstring:indexOfToken:indexOfSelectedItem: is called and its execution is very quick.

I would like to understand what happens and possibly improve this situation.

My question:

What does happen between textDidBeginEditing: and tokenField:completionsForSubstring:indexOfToken:indexOfSelectedItem:?

---

EDIT

Very strange: if I type ";" instead of "a", it goes much quicker! even though I did the following:

- (NSArray *)        tokenField:(NSTokenField *)tokenField
        completionsForSubstring:(NSString *)substring
                   indexOfToken:(NSInteger)tokenIndex
            indexOfSelectedItem:(NSInteger *)selectedIndex
{
    return @[@"Hello"];
}

Answer 1

I think it is a bug of OSX 10.9.

Here is what I did. The screen:

(the textField is a NSTokenField)

Then, in a delegate for this NSTokenField, put the following code

- (NSArray *)        tokenField:(NSTokenField *)tokenField
        completionsForSubstring:(NSString *)substring
                   indexOfToken:(NSInteger)tokenIndex
            indexOfSelectedItem:(NSInteger *)selectedIndex
{
    return @[@"Jojo!!"];
}



- (id)                        tokenField:(NSTokenField *)tokenField
       representedObjectForEditingString:(NSString *)editingString
{
    return @"Jojo the cat" ;
}




- (NSString *)              tokenField:(NSTokenField *)tokenField
     displayStringForRepresentedObject:(id)representedObject
{
    return @"Jojo" ;
}

You'll see, it bugs.